A range of magnetic latching devices utilising permanent magnets are conventionally known and find application in domestic settings as latches for cabinet and cupboard doors. Permanent magnets have also been utilised in magnetic couplings, and magnetic lifting, securing and clamping devices. Various types of rare earth magnets are nowadays readily commercially available. Rare earth magnets are strong permanent magnets and it can difficult to separate them from one another or from ferromagnetic materials due to the significant attractive forces they can exert.
Magnetic clamping devices are, for example, described in International Patent Application No. PCT/AU99/00070 (Publication No. WO 99/38726). That patent application relates to a device for securing a load to a motor vehicle, in which one of more permanent magnets are provided within a housing and are arranged to be raised or lowered with the rotation of a handle. The handle is in the form of an enlarged head of a bolt that protrudes from the housing and the permanent magnet(s) are alternatively lowered to magnetically clamp the device in position on the motor vehicle or raised to release the device there from, as the bolt is screwed into or out of the housing. However, screwing the handle to operate the device places a twisting force on the wrist of the user and the force required to overcome the clamping attraction of the permanent magnet(s) to the vehicle exacerbates strain placed on the wrist.